*{
    margin: 0;
    padding: 0;
}
html, body, .app{
    width: 100%;
    height: 100%;
}
body{
    background-color: rgba(240, 224, 224, 0);
}
.app{
    display: flex;
    justify-content: center;
    margin-top: 100px;
}
.upload-demo{
    display: flex;
    flex-direction: column;
    align-items: center;
}